1. Field of the Invention
The present invention relates to a multilayer piezoelectric element used in a fuel injection device or the like.
2. Related Background Art
In general, a multilayer piezoelectric element has a laminate body in which piezoelectric bodies and internal electrodes are alternately laminated, and external electrodes provided on side faces of this laminate body and connected to the internal electrodes. When a voltage is applied to the external electrodes, an overlap region (active region) between the internal electrodes of different polarities is deformed in the piezoelectric bodies. During driving of such an element, considerable stress concentration occurs at a border between the active region and an inactive region in the piezoelectric bodies, so as to facilitate production of cracks or the like extending in the laminate direction of the laminate body. For this reason, there are many proposals on multilayer piezoelectric elements with a stress relaxing layer in the inactive region of the laminate body, in recent years. For example, Japanese Patent Application Laid-Open No. 5-243635 describes a metal oxide layer formed as the stress relaxing layer by printing an alumina paste.